Experience w/C4D Hair System

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  04 April 2018
Originally Posted by Rectro: Nice to see someone having  a deeper look into the hair system, glad you found my tutorials helpful.

Id like to see some collisions for hair generated geometry instances, you can use the radius set quite high which works to some extent, but its not ideal.  Iv got some fair results using this method for hair cards with alphas on.  In my test I rendered strips of hair with alpha passes then used this for the texture.  With less guides, too few it can lead to hairs interpolating badly between the guides going through the mesh, however if you use the restrict to guides with the remove option this can sort this out.

One area which still causes me issues is the hairs lack of collisions, or at least the way in which each layer intersects causing horrible spec highlights.  Having to use clones, and frizz can get rid of most but its not ideal.  I would like to get hair guides from hair made in Maya into C4D to see how the guides influence this, or if its mainly down to the shader.  C4D own render engines render these intersections much worse than what I use for Vray.  Standard render, super fast but then it should be as it does not generate ray traced shadows, and to get any shadows you must use the light tag from the hair tags menu on a light source to get soft shadows in whcih 750 x 750 works a treat without this the hair looks flat.  The flatness of the way hair is layered may also be a issue as to why intersections are happening.  The hair interpolation works in a linear way from one guide to another, where as from what I see in Maya hair  around a guide not linearly only between guides.

Applying guides on polygon centre of per vertex also causes this linear placement of hair.  Without doubt using density maps produces the best results, and using the add guides with interpolation, radius of 0, placement of 1 lets you at least place guides in a  more random way. 

Dan

I think I accidentally overwrote my reply to you Dan. You are a bit further along with hair than I so I value your counsel!
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  04 April 2018
Originally Posted by IceCaveMan: ... if you render w/physical or a third-party renderer the hair must be converted to polygons--millions of polygons depending on your scene...
Just a clarification: some third-party render engines, such as Arnold and (I think) Redshift support C4D hair natively, and don’t require that it be converted to polygons.
 
  04 April 2018
Took 15 minutes for a little play on instancing. I can't immediately think of a real-world use for this outside of creating an alien planet, perhaps hair beads or pea pods... Perhaps someone more ingenious than I could suggest ideas. I didn't immediately see of a way to render the instances w/out the hairs.

If it had full mograph support with modifiers, falloffs and such...it could be more promising. Octopus arms and shit... 

Still...worth filing away for future reference.

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Last edited by IceCaveMan : 04 April 2018 at 04:23 AM.
 
  04 April 2018
Doh. The option to turn the hair offf was staring me in the face: toggle called: Render Hairs. 


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Last edited by IceCaveMan : 04 April 2018 at 02:06 AM.
 
  04 April 2018
Originally Posted by NWoolridge: Just a clarification: some third-party render engines, such as Arnold and (I think) Redshift support C4D hair natively, and don’t require that it be converted to polygons.
Vray does as well I believe. 
 
  04 April 2018
For those newer to hair.... image and video.

A simple dynamics scene using hair as grass. With dynamics. Nothing elaborate. Rendered w/Octane.



In years past hair was the go-to method for grass for any serious c4d artist. There are other options now and Octane Scatter is the bomb. Simple c4d hair can still work well.

Animation:
https://www.dropbox.com/s/vkjvc1z6z...namics.mp4?dl=0
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Last edited by IceCaveMan : 04 April 2018 at 02:22 AM.
 
  04 April 2018
Originally Posted by IceCaveMan: In years past hair was the go-to method for grass for any serious c4d artist. 

The trouble with using hair for grass is scalability. Large scenes require massive amounts of grass that is processed on a single core. Several extra minutes of processing time per frame is passable for still renders, but for animation? Troublesome. 
 
  04 April 2018
Originally Posted by LukeLetellier: The trouble with using hair for grass is scalability. Large scenes require massive amounts of grass that is processed on a single core. Several extra minutes of processing time per frame is passable for still renders, but for animation? Troublesome. 

Yes. Some would use a simple texture for distant grass and the hair-as-grass for in-close.
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  04 April 2018
We think of hair as good for linear objects, but in c4d it's not limited that way at all. (image & animation)



A French c4d artist who goes by nickname "French Monkey" has developed some crazy cool hair assets. Borrowing from his technique I quickly worked up an element, added a SSS material and tested it w/dynamics.

You'll notice there are two issues w/the dynamics in this animation. First there is a bit of imperfection w/the collision detection. Secondly the hair collision 'vibrates'...not settling down appropriately with time.  While there are several options for controlling hair physics I found no good solution to dampen the post-collision chatter w/out otherwise altering the interplay.

The hair system is great, but is getting a bit dated and that includes the physics engine, IMO.

If I was to take this scene further I'd consider converting the objects over and trying Soft Body dynamics.

Animation:
https://www.dropbox.com/s/blvna3rdd...lision.mp4?dl=0
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Last edited by IceCaveMan : 04 April 2018 at 04:28 AM.
 
  04 April 2018
I don't have any examples to share. Haven't used hair in years. But it looks like you've got the idea.
Instead of using cones of other shapes. I liked to use a polygon with a couple of cuts across it's with so it could bend like a strand of hair as the source object.
Then I would search the net for images that had transparent backgrounds.
I did a tutorial once many years ago using a feather image that had a transparent background that created nice looking bird feathers using instances that way.

-ScottA
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  04 April 2018
Originally Posted by Scott Ayers: I don't have any examples to share. Haven't used hair in years. But it looks like you've got the idea.
Instead of using cones of other shapes. I liked to use a polygon with a couple of cuts across it's with so it could bend like a strand of hair as the source object.
Then I would search the net for images that had transparent backgrounds.
I did a tutorial once many years ago using a feather image that had a transparent background that created nice looking bird feathers using instances that way.

-ScottA
I think years ago I did a feather and it sucked. Need to explore that again one of these days.
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C4D R19 Studio, MODO 902, VRAY, Octane, Cycles. PC/Mac.
 
  04 April 2018
Octane is working for me now in the high hair-count scene. And it's rendering 40% faster than the standard renderer. It does export the geo but that only takes 5-10 seconds. It renders all the geo crazy fast.

I guess I had a stay "wild hair" setting that was messing up before.
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Last edited by IceCaveMan : 04 April 2018 at 05:22 AM.
 
  04 April 2018
Originally Posted by IceCaveMan: We think of hair as good for linear objects, but in c4d it's not limited that way at all. (image & animation)



A French c4d artist who goes by nickname "French Monkey" has developed some crazy cool hair assets. Borrowing from his technique I quickly worked up an element, added a SSS material and tested it w/dynamics.

You'll notice there are two issues w/the dynamics in this animation. First there is a bit of imperfection w/the collision detection. Secondly the hair collision 'vibrates'...not settling down appropriately with time.  While there are several options for controlling hair physics I found no good solution to dampen the post-collision chatter w/out otherwise altering the interplay.

The hair system is great, but is getting a bit dated and that includes the physics engine, IMO.

If I was to take this scene further I'd consider converting the objects over and trying Soft Body dynamics.

Animation:
https://www.dropbox.com/s/blvna3rdd...lision.mp4?dl=0
I found turning on rigid dynamics works very well some slight movement in the hair, and of course itterartions, but steps is the one that calms the springs.  For grass simple scenes I use instance of a single geometry blade with dynamics on it.  Add wind force and turbulence and it works quite well.  Vray renders hair very fast, and even after adding an insain amount it dont seem to take much of a hit. 255k of hairs renders in little time.  Like you Id like to see much better physics.

Dan
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C4D R19 Studio, MODO 902, Zbrush 2018, Unfold3D 9,Marvelous Designer 7, Keyshot 6 pro.
 
  04 April 2018
Originally Posted by IceCaveMan: We think of hair as good for linear objects, but in c4d it's not limited that way at all. (image & animation)



A French c4d artist who goes by nickname "French Monkey" has developed some crazy cool hair assets. Borrowing from his technique I quickly worked up an element, added a SSS material and tested it w/dynamics.

You'll notice there are two issues w/the dynamics in this animation. First there is a bit of imperfection w/the collision detection. Secondly the hair collision 'vibrates'...not settling down appropriately with time.  While there are several options for controlling hair physics I found no good solution to dampen the post-collision chatter w/out otherwise altering the interplay.

The hair system is great, but is getting a bit dated and that includes the physics engine, IMO.

If I was to take this scene further I'd consider converting the objects over and trying Soft Body dynamics.

Animation:
https://www.dropbox.com/s/blvna3rdd...lision.mp4?dl=0
I found turning on rigid dynamics works very well some slight movement in the hair, and of course itterartions, but steps is the one that calms the springs.  For grass simple scenes I use instance of a single geometry blade with dynamics on it.  Add wind force and turbulence and it works quite well.  Vray renders hair very fast, and even after adding an insain amount it dont seem to take much of a hit. 255k of hairs renders in little time.  Like you Id like to see much better physics.

Dan
__________________
C4D R19 Studio, MODO 902, Zbrush 2018, Unfold3D 9,Marvelous Designer 7, Keyshot 6 pro.
 
  04 April 2018
Originally Posted by Rectro: I found turning on rigid dynamics works very well some slight movement in the hair, and of course itterartions, but steps is the one that calms the springs.  For grass simple scenes I use instance of a single geometry blade with dynamics on it.  Add wind force and turbulence and it works quite well.  Vray renders hair very fast, and even after adding an insain amount it dont seem to take much of a hit. 255k of hairs renders in little time.  Like you Id like to see much better physics.

Dan
In the example above I had steps cranked up. And I was using single hair collision.

Not sure but I suspect a limitation is that the detection doesn't take into account the geometric contouring of the hair. Conversion to standard mesh and soft body collision might be the only solution here.
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